Pd-Catalyzed Synthesis of Fluoropiperidines

Significance

Reported is the palladium-catalyzed intramolecular aminofluorination of unactivated alkenes 1 to give 3-fluoropiperidines 2. Substrates with either one (R^² = H) or two (R^² ∂ H) substituents at the β-position were well tolerated. Two examples containing disubstituted alkenes (R^¹ = Me) were also shown to proceed in high yield. Opposite diastereoselectivities were observed in the reaction of trans-3 and cis-3 under the standard conditions. Substrate 6, containing one extra methylene unit in the linker, demonstrated a preference for 7-endo cyclization over 6-exo, in moderate combined yield.